High-tension wires are strung from a power source through a maze of electrical suspension towers and telephone poles, in order to transfer power from the source to the consumer. In order to string the high-tension wires, electrical stringing blocks are installed at towers or powerpoles for overhead transmission and distribution lines for pulling the wires. A lead rope is strung through the electrical stringing blocks, either manually or by a helicopter. Then, the lead rope is exchanged by a single or bundled conductor forming the wire, running on the electrical stringing blocks. Finally the wire is transferred from the electrical stringing blocks to clamps.
Standard construction for an electrical stringing block include cast aluminum sheaves or molded nylon sheaves, supported by bearings on a solid axle, suspended in a cast or fabricated metal frame. The sheaves have a plurality of spokes, which are optimized for casting. The weight of cast aluminum sheaves is quite significant, particularly in the case of larger diameter sheaves.